A very common deficiency found on concrete tile roofs is the sliding of tiles that were originally in contact with a hip or ridge board. This commonly happens because the tile has been cut down in size to accommodate the space needed to fill between the adjacent tile and the angled hip rafter. This cut always eliminates one or both of the anchor “cleats” on the top of the backside of the tiles. With no factory anchor to hold the tile in place, the original installer usually just applied a mastic sealant between the tile and the wooden hip board. Sorry to say this doesn’t work. The pull of gravity moves the cut tile. When the old mastic stretches, dries and breaks the tile is left to slide out of place and opens up a void in the roof system and a potential leak! The proper way to anchor these tiles is to grind a notch, or better yet two notches, in the tile and nail on a diagonal into the wooden hip rafter. This is what we accomplished today on this Richmond house. There is no way this tile is going to move.